We are excited to announce a set of new capabilities for
AWS CloudFormation; validation for template parameters, resource deletion policies and the ability to block stack creation until your application is ready.

Some applications need time after an
Amazon EC2 instance is launched, before the application is considered ready to take traffic or perform operations. AWS CloudFormation templates now provide a
WaitCondition resource that acts as a barrier, blocking the creation of other resources until a completion signal is received from an external source such as your application, or management system. Also, when a resource is deleted, you now have options to keep any of the stack resources around or to snapshot
Amazon EBS volumes and
Amazon RDS database instances before they are deleted.

We provide
example templates that illustrate each of these new features and let you get started with only a few clicks in the
AWS Management Console. The sample application templates have been updated to include parameter validation, making it easier for you to create stacks quickly.

To see some of these features in action, check out this
article that shows how to use AWS CloudFormation and the cloud-init feature supported in
Amazon Linux AMI to launch a Ruby application at stack creation time.